Wealthy parents aren't just able to send their kids to top pre-schools—they can also purchase the latest learning technology and ensure their children experience as many museums, concerts and other cultural experiences as possible. Low-income parents, on the other hand, don't have that opportunity. Instead, they're often left to face the reality of sending their kids to schools without having had the chance to provide an edifying experience at home.

That might sound foreboding if not hyperbolic, but it's a serious and widespread problem in the United States, where poor kids enter school already a year behind the kids of wealthier parents. That deficit is among the largest in the developed world, and it can be extraordinarily difficult to narrow later in life.

This is one of the key takeaways from a new book about how United States is failing its children. The book, called Too Many Children Left Behind, is written by Columbia University professor Jane Waldfogel, a long-time researcher of poverty and inequality. And it will force almost anyone to reflect on the impact of unchecked inequality on children.

Waldfogel says the massive achievement gap in the United States is a blemish for a country that aspires to be the greatest in the world. In her book, she shows that achievement gap is pronounced to a startling degree in the first years of life.

I spoke with Waldfogel to learn more about how the early years of a child's life can impact the rest of it, what role school plays in perpetuating inequality, and why the United States isn't doing a great job of creating an equal playing field for its children. The interview has been edited for length and clarity.

Let's start with a provocative question you ask early on in your book: Is the American Dream a reality for everyone, or only for some? Do you have an answer now?

The American Dream is based on the belief in equal opportunity, the idea that everyone starts from the same starting point regardless of where they’re born or their family background. If there are systematic differences in children’s capabilities, starting even early on in childhood, then that’s going to impede achieving the American Dream. So it just seemed important to us to look at that.

There’s so much work showing greater inequality in the United States among adults, among adolescents, even among school age children, but it’s not clear where that inequality comes from. If you had asked us at the start of the project, we would have said that children probably arrive at school somewhat unequally prepared because of the difference in their experiences in early childhood, but that the achievement gaps were also largely due to schooling. We would have guessed that about half the inequality that you see in young adults or adults more generally would be there at school entry, but that at least half of it would develop as children move through school—because of all the things we know about schools and unequal experiences at schools.

The big surprise for us was to find that more than half of the inequality was already there at school entry. The schools are not as much to blame as we had expected. And that’s not true elsewhere. The United States really stands out, not just in having more inequality at school, but having more inequality even in early childhood. So something is happening in the very early years of life that’s pulling kids apart, and that’s happening more so in the United States than in other countries.

The United States is somewhat of an exception in that a lot of parents don’t send their kids to preschool. How does that play into this?

A lot of people have commented about what they call the problem of the family, and that’s that families are unequal and very highly motivated to invest in their children, to do all they can to invest in the prospects of their children. So if you put those two things together—that families have unequal resources and all of them are motivated to do the best they can for their children—left unchecked, that’s going to produce quite a bit of inequality by the time children show up at school.

Now, one of the forces that can counteract that is a universal experience that is equalizing. And that’s why preschool can play such an important role. It’s a place where the United States differs dramatically from other countries, because virtually all of our advanced, industrialized peers have universal preschool. Whatever age their children start school, 90-something percent are in free public preschool the year before school entry and the year before that.

We’re so far from that. Right now, just under 30 percent of four year-olds have access to something that looks like universal, publicly funded preschool. The percentage for three year-olds is minuscule.

What we have instead is preschool enrollment and quality very much reflecting parental resources. So the kids of the most affluent, of the most advantaged parents, they’re in preschool, and they’re in very high quality preschool, because their parents can afford it. Whereas other kids—those in the middle, but especially those at the bottom—are in poorer quality care, or they might be in informal care, they might be in a patchwork of arrangements—with a relative or a baby sitter or someone else. All of this is to say that the experiences they have are very much lined up with their family resources, and they’re very unequal.

So instead of preschool playing an equalizing role like it does in other countries it is actually contributing to the inequality in our country.

How serious is the achievement gap between poorer and wealthier children in the United States?

It’s pretty frightening.

We find that for both reading and math, the children whose parents had low levels of education—meaning they only got a high school education or less—are lagging behind the children of more educated parents by a full standard deviation at school entry. A standard deviation is huge—it’s a big gap; it’s at least an entire year of development.

By comparison, in the other countries we looked at, the gap was closer to half a standard deviation. So the gap is substantially and significantly larger in the United States.

Wow. And we’re talking about kids who are only four years old. So four years in to life they are already a full year behind?

Yes, it’s terrible.

In your book, you talk how detrimental this gap is. It’s even more impactful in terms of its contribution to inequality than the gap caused by different levels of schooling. Is that right?

It is. We went into this thinking that whatever the gap was at school entry, that that would make up about half of the achievement gap we saw at the end of the school years. It was just kind of our guess, since no one had looked at this systematically in prior research. But it turns out we were far off. The gap at school entry is responsible for 60 or even 70 percent of the gap seen at the end of the school years—it’s a much more severe contributor than we had imagined. And that really makes it all the more important that we address it.

The United States is somewhat exceptional in this regard. Can you talk a little about how the size and shape of the achievement gap in this country is distinctive?

Where the United States really stood out was in having significantly more inequality at school entry and at the end of school compared to peer countries we found around the world—those are Australia, the United Kingdom, and Canada. For most of the things we looked at, the U.K. was in second place behind the U.S. in terms of the level of inequality. Australia and Canada really stand out as having much more equality of outcomes among kids than the United States. And this is carried through as kids go to school. The achievement gap grows as kids go to school in the U.S., but it doesn’t really elsewhere.

Some of this is just what is going on in the families. There is more inequality in family resources—when you look at things like teen parents, kids experiencing change in their family structure growing up, and especially family income—which go hand in hand with parental education, in the U.S..

In all of the countries we looked at, income and education were strongly linked, but nowhere was it anywhere near as indicative as in the U.S.. Highly educated parents have much higher incomes than those in the other countries, and lower educated parents have much lower incomes than those in the other countries. The extent to which your parent's education is linked up with financial resources is much stronger in the United States. So we just have more inequality to start with.

Unfortunately, when we look at the public policy side, we do less to address the inequality than they do in other countries. We transfer less resources to low income families, we don’t have universal preschool, and we’re just generally doing less to counteract the intense inequalities.

You talk in the book about how luck and circumstance plays into someone’s ability to achieve their goals in the United States. Are there specific or subtle ways in which this plays out that people might not realize?

What’s been happening, especially in the United States, is that we’ve seen a growing divergence in parents’ investment in learning-related items. There’s been a lot of attention in the past view decades on early development and early brain development and the importance of the early years. The more educated and affluent parents have really taken this to heart, and they have the resources to do something about it. So there’s been an explosion in investments, in things like computers and toys and all sorts of learning-related enrichment items. There has also been an increase in activities, like taking kids to museums, to art classes, to music classes—you name it.

But the low income families have not been able to keep pace. They just don’t have that kind of discretionary income to pay for these kinds of activities. So that’s one pretty important mechanism people might not understand.

We’re also learning all the time about the negative affects that financial stress have on health and development, in terms of the presence of stress and depression. The lower income families are dealing with much higher levels of financial instability and hardship. That takes a toll on the parent’s health and the children’s health.

So it’s both the absence of the enriching activities and expenditures, and the detrimental effects of low income financial stress and financial hardship.

I don’t expect a simple answer to this, but it seems like the natural next question: How do we fix this?

We clearly have to do something within early childhood to even out these kinds of inequalities. If we’re going to be spending money on early childhood, we want to spend it wisely. So we looked at and reviewed the evidence to find policies that we know would make a difference in helping promote the achievement in young children of less advantaged families.

The two that we really emphasize are evidence-based parenting programs and high quality preschool for three and four-year olds. There are a bunch of other supports that matter in early childhood, the most prominent of which is paid family leave, which the three other countries have and our country does not.

Then there’s obviously an agenda in improving schools, especially schools for less advantaged kids. Part of that involves recruiting, supporting, and more adequately compensating effective teachers, implementing a more rigorous curriculum, and setting a higher standard and level of support for lower achieving students.

We have a tendency in this country to dismiss those lower achieving students—we put them in separate tracks or separate classes—and what we’ve seen around the world is when countries implement more comprehensive forms of education, where all the students have to take the same rigorous classes, everybody ups their game. Even the lower achieving students overachieve if those expectations are set, supportive measures are taken, and high quality teachers are put in place.

And then cutting across early childhood and the school years is doing something about income. As we’ve talked about, a lot of what’s going on in the United States is the greater inequality of incomes and the much higher child poverty rate than you see in other countries. So we have got to do something about raising family incomes for low income families. That involves things like raising the minimum wage, expanding support systems we have for families that go alongside that, making sure that we keep and strengthen the food and nutrition programs, and then, if families are going to be able to stay in work, we have to make sure their work is not disrupted by family responsibilities, which is why something like paid leave is so important.

In the book, you talk about how hard it is to reverse the course set in the first years of life. Do we not appreciate the importance and impact of what happens early on in a child’s life? Do our policies reflect an apathy toward the importance of these years?

I think I’m a little more optimistic than that. I think there’s actually widespread recognition now about how important the early years are, and I think that’s going to help create change. I think among policy makers there’s a greater recognition now than there used to be about how important the early years are. Where we get stuck is that we aren’t so sure about what we should do about it. We haven’t had good data on early childhood until very recently. The kind of data we used, looking at a nationally representative sample of kindergarten children as they started school, it’s the first time we’ve had this kind of data.

Now that we know important the early years are, we’re starting to think about how much inequality is there in the early years, and what there is that we can do about it. Until recently, we didn’t have a very strong evidence base about what we could do about it.

I guess there have also been some political barriers, in terms of who is responsible for early childhood. There’s a debate about whether this is the responsibility of the family, and whether government should even get involved. With schools, in some ways it’s easier, because the children are in school. The question then is are we spending the money wisely, and what kind of school should we have, and what kind of curriculum.

But with most kids zero to five, they are not being seen and not being served. We have to first answer the question of whether government should do something with them, or for them, and then, if so, what. We’re all just kind of piecing it all together.

I know that your research has looked in the past at the impact of government assistance programs. And these programs are often villainized. Does the villainization perpetuate the sort of inequality we see in early childhood?

I think we have not well understood the role that these food and nutrition programs play in promoting child health and development. I think policy makers and even researchers have focused on more of the first order questions. When we authorize programs, like say the food stamp program, we ask things like are benefits reaching recipients and are they reducing hunger or improving nutritional adequacy, and are there any negative consequences in terms of working incentives and fraud and abuse in the program. Those are the kinds of questions we think about, and that’s fine—if you ask people what the purpose of the food stamp program is, they’ll see it’s to alleviate hunger in the United States, which is an incredibly worthy goal.

But it turns out that getting food stamps probably also improves children’s health and development, and improves their school achievement. And we haven’t really looked at those things—we’re just beginning to. Because we have ignored those kinds of effects, we necessarily undervalue the programs. Even with something like school meals, we’ve mainly looked at whether they are being eaten and whether they are improving nutrition and combating hunger. But there’s a whole other set of questions that include things like whether giving kids meals improves the chances that they show up to school, and whether they do better when they’re in school.

I’ve been surprised by how little research there has been on these kinds of health and development effects. And the extent to which we’re ignoring them is contributing to the severity with which we undervalue these programs.